Safety control mechanism for electrically-controlled fuel-burning devices



A ril 6, 1926. 1,519,197

l... l. ALDRICH SAFETY CONTROL MECHANISM FOR ELECTRICALL CONTROLLED FUEL BURNING DEVICES Filed Sept. 19, 1923 for 967 Lo- In:

:i h :i .70

uen zol' ber.

Patented Apr. 6 1926.

Int-79,497

-UNITED. STATES PATENT oFFicEL -LOYD I. ALDRICH, or rnonm, ILLInoIsnssIenonr'o IIAM OII numn 00., on

' rnonm, ILLINOIS, A oonromrxon or ILLINOIS.

SAFETY 'COIT'IROL MECHANISM FOR DEVICES. v

Application filed September 1,9, 192:." Seria1 1i'o.668,576.

To all whom it concern:

Be it known that LOYD I. ALDRICH, a!

citizen of the United States of .America,"re siding atPeoria, in the county of Peoria and State of Illinois has invented certain new and usefulflmprovements in' Safety Control Mechanism for Electrically-Con-.

nism mounted'in a combustion chamber,'or rather mounted in such position as to be 3 affected by the combustion conditlons in said chamber and co operating with a conventional electrically operated fuel burning device.

-Another object of my invention 1s in the provision of a thermal safety control mechanism co-operating with 'a-formal liquid fuel atomizing device in such manner as to control the operation thereof entirely from. combustion conditions. Y

A-still further object of my invention ,is in the provision of a thermal safety contnol mechanism co-operating 'with an electrically operated fuel burning device and the 1 gn1- tion means therefor, whereby either initial failure of ignition or.- lack of combustion conditions will result in the operation of saidsafety mechanism to break the circuit to saidfuel burning device. r

' Yet another object of my invention is in the special formation of my "safety control member whereby an'increased sensitiveness to temperature conditions results.

in the following specification taken in connection" with; the annexed drawings, in which:-* r

Figure 1 is a [side elevation partially in section of my thermal safety controlfmenb Figure 2 is burning outfit and electric connections there- Other objects of my invention will appear but partially as at 16.

My present safety control means for fuel burners-is an improvement upon a similar control mechanism disclosed in my .co-

pendingapplication, Serial Number 632,541,

filed'April 16th, 1923, entitled Safety control mechanism for liquid fuel burners.

, In Figure2, I have illustrated my safety control mechanism in (lo-operative relation with my fuel burning device and control means therefor and in a co-pending application, Serial Number. 647 ,444', filed June 25th, 1923, entitled Liquid fuel atomizers, a

complete description of said fuel burning device and control means is contained. In

View of the fact that a full description of the fuel burner and its electric connection has been -made in a co-pending application a'nd as my present device includes mainly the safety control mechanism, per 'se, Ihave not thought it necessary to o to too great detail inthe description of sa1d fuel burning mechanism. j

Briefly, my fuel burner mechanism includes an electric motor :10, as a-power unit. A flexible connection 11 provides means for transmitting power to the burning device which includes an" air-pump 12,8. rotary fuel pump 13 and a common tube 14, which carries the mixture of air andfu'el under.

pressure throu h a discharge pipe 15, to the a formal combustion chamber, the :combustlon chamber in the drawings being shown;

My fuel-burning devicehas for its igni-.

tion means agas pilot which is ignited by a 5 spark mechanism, the whole ignition program taking place. upon the initial moveporarily thereafter, there being means for zmentof the burner and continuing-but tem 7" c'ontrolling the-time necessary for igniting I "the discharged fuel mixture. Generally the fij ignition means is shown. at 17, adjacent the;

a detail showing ofa' chamber. Inasmuch as' myfuel burning de discharge nozzle -wi thi-nf7thecombustion.{ I

vice 'iselectrically ic'ont rolled 'ftherej are 'in- 4 eluded some main-electrical port-ionsth'at I" have become practically j-formal to electri callycohtrolled fuel burnerjoutfits. .iThe'se" so discharge nozz e 17 which is disposed within cated in any portion of the house or building where it is desired to maintain a uniform temperature.

The electrical circuits for the-burning device include a high voltage circuit, usually 110 volts, coming in from the street, and a low voltage circuit, which includes the transformer 19. A relay switch 21 controls the supply of current from the transformer 19 to the electric motor 10 and the control circuits associated therewith. This relay switch, diagrammatically shown in Fig. 2, comprises a main switch bar 21 pivoted at 50 in such manner as to control the movement of the two-sub-switches 51 and 52 carrying contacts 55 and 70, respectively. The- I These solenoids carry the plungers 48 and 49 so positioned that the upper ends thereof are adapted tofcngage the under sides of the opposite ends of the main switch. If the solenoid 21 is energized, its plunger 49 moves the switch to closed position, and, upon deenergizing of the magnet, the plunger drops back, leaving the switch in closed position. If the other magnet 21 is energized, its

plunger 48 moves the switch to open posi- I tion. The plunger 48 in this magnet isalso operatively connected to a gas supply valve 54 by a link 53, which valve controls the supply of gas to the pilot light of the burner.

A safety switch mechanism 20 cooperates with the main switch mechanism in the fol lowing manner: The plun er 48 in the solenoid 21" carries a bi-metal icstrip 21 which is adapted to close a circuit through the terminals 57 and 58-when the solenoid winding is heated by the energizing current flowing therethrough. The magnetic coil20 coacts with. an armature 20 provided with a hooked lower end as shown which is adapted to engage a pivoted latch member 20 carrying an insulated contact 7 3 positioned to make contact with the terminal 72 when members 20 and 20 are in latched position.

In operating thesafety switch, the expansion of the bi-metallic element on the, plunger 48 of the solenoid 21", due ;to heating of the winding, closes a circuit throu h the leads 76 and 7 6 and hence through t e Y as coil 20 which attracts its armature 20, thus releasing the latch member 20 and breakingv the contact connection between the terminals 72 and 73,and thus opening the circuit of This diadinal arm 62 at the inner end of which is a slip connection 63 with the arm 64 pivoted at 65 to the vertical lug 66. A substantially vertical lever 69 is pivoted to the outer end of the arm 64 and 1s reciprocable by-movement of the diaphragm within the guideways 67 and 68 The purpose of the lever 69 is to raise the outer end 50 of the main switch 21 whereby toactuate the sub: switches. i

The structural features of my electrical control mechanism have been set out, and I will now describe the operation of the various switches and the circuits which they control. There are two leads 74 and 75 from the 110 volt supply line'which are connected respectively to the relay or main switch 21 and the safety device 20 operated by the heating of the thermal elementin the plunger 21". The 110 volt side of the transformer 1.9 is so connected to the line wires that both the main and safety switches in the 110 volt circuit must be closed in order thatourrent may be supplied to the transformer and to the motor operating the fuel pumps. J

The transformer l9 is. also provided with a low voltage top of 12 volts to which the 4 leads 76 and 77 are connected. These leads supply the current -to energize the. solenoids. 21 and 21,and also the magnet 20.

The safety switch functions to automatically disconnect the 110 volt line if current usual house thermostat switch'18 located at any desired point, through said switch if closed to the on coil, through its winding, and to a furnace thermostat 22, which, 1f closed, allows the current to return to the transformer. The house thermostat 18 and the furnace thermostat 22 must have their switches in closed position simultaneously in order that current may energize the on coil and operate the" main switch. The

plunger 48 of this coil, due to its upward movement, closes the main switch, opens the gas valve 54 through the linkage 53to'supply the pilotflam'e for ignition purposes and maintains these parts in such positionuntil the on coil becomes demagnetized when its circuit is opened by either the house thermostat or the furnace thermostat.

As previously explained, when the main switch is moved by coil 21 to the on position, it carries with it a pair of movable contacts 70 and 55 on the sub-switches 51 and 52 which engage insulatedterminals 56 and 71, rep'ec'tively. The main switch is initially actuated by a current which is flowing through the house thermostat 18, but since it is not desirable to permit such current to flow therethrough for an appreciable length of time, one of the sub-switches is arranged toshort circuit the leads to said thermostat.-

The off coil or solenoid 21 is connected in a circuitwvhich includes the low voltage tap of ,the transformer, the switch of the room thermostat 18, the insulated terminal 57 and the'sub-switch 51. From an inspection of Fig. 2, it will be seen that this circuit 7 can be broken either by the main switch being moved'to its off position, or b "the opening of the house thermostat switc 1 due to a lowering of the room temperature. The circuit breaking switch is closed only "when the main switch is in its closed position. A rise in room temperature closes the contacts of the thermostat 18 andcauses a current to flow through the off coil 21, lifting the plunger 49 and tripping the main switch. This movement also opens sub-switch 52, de-

energizes coil 21", and permits the plunger 48 to drop back to its initial position.

The above description of t e main portions of my fuel burning device has been given mainly to show the co-operation of my present thermal safety control mechanism, and it may be seen that generally the house thermostat thru the relay switch controls the starting and stopping of the fuel burning device. However, in all fuel burning outfits there must be some control mecha-- nism and it is in the control mechanism for the above device that my present structure has been developed. I

The object of the safety mechanism is to prevent the operation of the fuel burning device and hence an unignited flow of fuel into the combustion chamber either when there is an initial failure of ignition or in the case of a' failure of combustion conditions.

during the operation of the device. My present thermal safety control mechanism is perhaps more properly named a furnace thermostat inasmuch as there is a temperature control means for making and.

breaking an electrical-circuit.

.Although in Figure 2, I have shown my present safety control member as projecting into a combustion chamber at a point near the discharge end of the fuel burning out-fit, however, this is not the only place adapted for its insertion and as a matter of; fact, it is usually located at a more convenient point, namely: in the smoke pipe of the ordinary furnace. My safety control member or furnace thermostat is composed of a housing portion 22 which encases the contact portions-to be laterdescribed. Screw threaded into a projecting portion 23 of the casing is a hollow metal tube 24 having a closed end 37. Loosely mounted in the brass tube is a cylinder or rod 25 of carbon or some other substance. having a smaller co-efiicient of expansion than the metal tube. Abutting stance is a plunger 26 having an inwardly pro ectin stem 27 abutting the multiplying lever 28 ulcrumed at 29 within the housing 22*. Abutting' the opposite side of the multiplying lever, and at the opposite end there- 'The upper end of the pivoted yoke provides the inner end of the. non-exp-ansible sub- I the contact portion 43 of the safety mechanism and said yoke is adapted to oscilate between the insulated contact point 44 and the projecting lug 45 within the casing. The electrical connections to my safety control member are shown at 46 and47 audit may be clearly seen, that the movement of the yoke 40 is adapted either to make or break the electric circuit.

As stated before my safety control mechanism is adapted to operate either upon initial failure of ignition or later upon failure of combustion conditions and it may be clearlyseen that it is the effect of combustion conditions upon the hollow metal tube 24 thatefiects the operation of the yoke 40 to make or break the electrical circuit. As

stated before in the case of failure of'ignition of the sprayed liquid fuel upon commencement of operation of the fuel burning device, the time switch located in connection with the relay switch and safety switch will remain in circuit due to making ofcontaet between the oke 40 and insulated contact point 44, and eventually. throw out of circuit the electric motor providing power means for the, device, unless said contact is broken in the-safety control member. Un

der normal operation, with an immediate ignition of the discharged fuel mixture.

temperature will be raised within theconr bustion chamber and said temperature will directly effect the metal tube 24 with the result that the consequent expansion thereof will permit the carbon cylinder 25 contained therein to move outwardly due to the pressure of the spring 38. The multiplying lever 28 will be moved by the shiftable rod 37 to the right, said rod carrying with it the sleeve 36 thereon, themovement of which thru the action of the spring 38 forces the yoke to the right and thereby breaks the contact between the yoke and insulated point 44. It may be seen that the initial movement of the sleeve 36 carries the yoke with it thereby causing either a making or breaking of the contact, however, permitting further extension of the rod 37 in either direction.

\Vith the breaking of the contact in my safety control member due to the sensitive ness of the metal tube to the changes in tempera-ture, the time switch briefly referred to, is thrown out of circuit and the fuel burning 'deviceis capable of continuous operation until checked either by the house thermostat or by a failure of combustion conditions that might subsequently effect my safety control member.

The above operation of my safety control member or furnace thermostat is thought clear, relative to the operation of the fuel burning device, in case of initial failure of ignition. However, relativeto the failure of combustion conditions after initial ignition of the fuel mixture, I will say that under such conditions the consequent cooling of the brass tube results in a contraction thereof with the result that thruthe series of plungers and levers the contact is 'made between the yoke 40 and the insulated 0on tact point 44: thereby placing in circuit the time switch which after a determined period will throw out the safety switch connected therewith to break the electrical circuit including the electric motor and hence stop the operation of the device.

What I claim is:

1. A fuel burning device comprising means for projecting a fuel mixture into azone of ignition, a combustion chamber, an electrical safety control mechanism" for preventing the projection of the fuel mix= ture upon an initial failure of lgnition or a failure of combustion conditions thereafter, said safety control mechanism comprising a switch including a movable 0on tact member, a thermal member sensitive to combustion conditions for controlling the movement of said member, and a slip-connection. between the thermal member and the movable contact member for substantially immediately actuating the movable contact member upon initial movementof the thermal member in either direction. i

2. A fuel burning device comprising means for projecting a fuel mixture into-a zone of ignition, a combustion chamber, an electrical safety control mechanism for preventing the projection of the fuel mixture upon initial failure of ignition, said safety .the movable contact member for substantocombustion conditions for controlling the "movement of said member, and a yielding connection between the member sensitive to combustion conditions and the movable member for substantially immediately actu ating the movable member, upon initial movement of the member sensitive to combustion conditions, in either direction.

4. A fuel burning device comprising means. for projecting a fuel mixture into a zone of ignition, a combustion chamber, an electrical safety control mechanism for preventing the projection of the fuel mixture upon an initial failure of ignition or a failure of combustion conditions thereafter, said safety control mechanism comprising separable contact controlling the electrical circuit, a movable member adapted to control the electrical circuit through said contacts, a thermal element sensitive to combustion conditions actuating said movable member, said parts being so arranged as to substantially immediately make or break the electrical circuit upon initial movement of the thermal member in either direction.

5. A fuel burning device comprising means, for projecting .a fuelmixture into a zone of ignition, a comb'ustionchamber, an electrical safety control mechanism for preupon an initial failure of ignition or a fail ure of combustion conditions thereafter, 7

said safety control mechanism comprising separable contacts controlling the'electrical circuit, a movablecontact member adapted to control the electrical circuit through said contacts, a member sensitiveyto combustion conditions for actuating said movable member, said parts being so arranged as to sub-' stantiallyimmediately make or break the electrical circuit upon initial movement of the membersensitive to combustion conditions in. either direction.

6. A fuelburning device comprising means for projecting a fuel mixture into a 4 zone of ignition, a combustion chamber, an

' of combustion conditions thereafter, said safety control mechanism comprising an electrical circult, a switch in the same, and a thermostatic element responslve to the temperature of the combustion chamber which opens the switch upon a rise in temperature and maintains 1t open during con- 'stant or increasing temperature, but closes said switch substantially at the commencement of any fall in temperature. In testimony whereof I afiix my signature.

LoYD I. ALDRICH. 

